That's because the weather module is unfinished, possibly even pre-beta material.
Luthier once said it would be completely omitted from the initial release, the only reason it's there is that a lot of us asked for it so they gave it to us in a sort of "use at your own risk" way, just to experiment. In other words it's not meant to work well, it's just the early rough draft they were working on and only got released because of community pressure, so that we could experiment with it.
